JPS59101672A - Copying machine - Google Patents

Abstract

PURPOSE:To obtain copying of a good quality by detecting a reflecting density of a ground of a copying original by preceding a copying process, and executing by a constant optimum developing bias voltage in the course of an operation of the copying process by its detecting output. CONSTITUTION:A sensor 19 converts a reflecting density of a ground of a copying original 12 to an electric signal, supplies it to a processing circuit 23, and adjusts it to a correct developing bias voltage through a controlling circuit 24 and a developing bias power source 10. Thereafter, when an exposure lamp 13 is turned on and the first optical part 20 moves to a point B from a point A, the exposure process is started, and the copying process is completed through development, transfer and fixing processes. In the course of an operation of the copying process, the optical part 20 executes a reciprocating motion between the point A and point B, but since the sensor 19 and a sensor holding member 21 are moved to a point D, there is no hindrance in the operation of the optical part 20. When the copying process is ended, the optical part 20 stops at the point A, the post-processing process is executed for several seconds, and thereafter, the operation is completed, but within the execution time of the post-processing process, a sensor holding member driving mechanism 22 is operated in the opposite direction, and the sensor 19 is reset to the point A from the point D.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electronic copying machine having an automatic exposure feature.

The structure of the conventional example and its problems ``In electronic copying, as shown in Fig. 1, the photoreceptor drum (
i), a charging section (2), an exposing section (3), a developing section (4), a transferring section (5), and a fixing section (6) according to the copying process.
, and a cleaning section (7) are generally provided.

As shown in Figure 2, the surface potential of the drum (υ) is determined by the band action at the charged part (2), and by the exposure action at the exposed part (2). It shows V7 in the image area, and J in the background area other than line drawings.In addition, since a pressure vB is applied to the magnetic roll +81 due to the phenomenon bias Uυ, the magnetic blank is applied to the photoreceptor drum (1). (9), the developing bias pressure VB is applied.For this reason, the surface potential seen from the magnetic brush (9) is CvIB-
vs), picture 9m-T:trl+cV2-VB) tfx
(D-C1) Negatively charged toner does not stick to the photoreceptor drum (υ) due to repulsive force in the background area, and is copied white, and in the image area, due to the positive surface potential, it attracts one toner and is copied black. On the other hand, if the copy original is paper that does not require diazo reproduction, or is made of color paper, etc., the surface potential of the background part of the copy manuscript is V: ), and the surface potential as seen from the magnetic plan (9) is +(V3-Vn), toner is absorbed and causes a background cover, which is inconvenient for copying.For this reason, in general electronic copying machines, the light intensity of the exposure lamp is adjusted according to the copying original. Methods are used, such as changing the surface potential v3' of the background part to make it lower than the bias voltage Vn, or changing the bias voltage so that the surface potential v; of the background part becomes higher. Generally, in electronic copying machines, one of the above two methods is added as an exposure adjustment device, and the user of the electronic copying machine sets the exposure adjustment device to the appropriate state depending on the original to be copied. By setting the exposure adjustment device to , it is possible to obtain high-quality copies without background fog, but skill is required to set the exposure adjustment device to an appropriate state depending on the various types of originals to be copied.

In order to improve the above-mentioned drawbacks, a self-address copying machine with an optical function has been proposed, an example of which is shown in FIG. A part of the copy original (121 molecules) placed on the original table glass (1) is irradiated with the exposure pump OJ, and the first mirror 04
The light 4r4 is applied to the lens α by the mirror α5) of the I5 light 2 and the fifth mirror 06), and is further subjected to slit exposure to the photo drum (1) through the fourth mirror a. The exposure lamp (
131 and a first optical part I201 including a first mirror circle
starts moving at a constant speed and sequentially illuminates the copy document UZ from point (A) to point (B). On the other hand, the first optical section I
The sensor Q91 installed in the front of the 20) detects the background of the copy original (121), and uses this detection output to change the exposure lamp Ll: The exposure state is automatically determined by changing the pressure.

However, according to such a configuration, sensor Q9)
Since the time during which the background of the copy original L121 is detected and the time during which the copy original 112) is automatically exposed are different, a case may occur in which the % exposure state is partially inappropriate.

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and enables high-quality copying work without mistakes by accurately detecting the background of a copy original and automatically setting an accurate developing bias voltage corresponding to the copy original. It is an object of the present invention to provide a copying machine that can realize the above functions without reducing the copying speed, which is the basic performance of the copying machine, at all.

SUMMARY OF THE INVENTION In order to achieve the above object, the copying machine of the present invention includes a sensor that detects the reflected density of light from a copy document, and a sensor that detects the density of light reflected from a copy document, and a sensor that detects the density of light reflected from a copy document. a sensor moving means for moving a predetermined distance along the lower surface of a document platen glass, and determining a developing bias voltage based on a detection output of the sensor during movement;
The apparatus further includes a control means for controlling the developing bias voltage in accordance with the reflection density of the background of the copy document.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 4 and 5, the same components as in FIGS. 1 and 6 are denoted by the same reference numerals, and the description thereof will be omitted. In FIGS. 4 and 5, L22+ is a sensor holding member, L22+ is a sensor holding member drive (imaginary, M is an arithmetic processing circuit, and 2 and phantom are control circuits. Generally, in an electronic copying machine, the parts other than those shown in FIG. 5) are 4i by pressing the copy operation start switch
Perform the J treatment step for a few seconds. In this embodiment, the time for performing this pre-processing process is used to rotate the sensor holding member drive mechanism, which is composed of gears, etc., in the forward direction within that time, and the sensor holding member drive mechanism is rotated in the forward direction, and the sensor holding member drive mechanism is rotated in the forward direction, and the sensor holding member drive mechanism, which is made up of gears, etc. The sensor α9) installed as shown in FIG. As sensor 09),
lamp.

A reflected light sensor is used, which is a combination of a light emitting element such as an LED and a light receiving element such as CdS or a phototransistor. This sensor +191 converts the reflection density of the background of the copy document α2 into an electrical signal and supplies it to the arithmetic processing circuit (c). The arithmetic processing circuit UJ arithmetic processes this electric signal and supplies it to the control circuit j44+, and the control circuit example changes the developing bias C pressure supplied according to the developing bias image συ and adjusts it to an appropriate developing bias voltage.

After that, the exposure lamp 03) is turned on and the first optical section 1
20) starts moving from point (A) to point (B), thereby starting the exposure process, followed by development, transfer, and fixing processes, and then the copying process is completed. During the operation of the copying process, the first optical section 120) reciprocates between points (A) and (B), but the sensor l1llll and the sensor holding member brush (moves to point D> Therefore, the first
There is no problem in the operation of the optical section 120). Furthermore, when the copying process is completed, the first optical group stops at point (A), and after the post-processing process is fired for several seconds, all processes of the copying machine are completed and the operation is completed, but the post-processing process During the implementation time, the sensor holding member part! ! II ta 44It- operates in the continuous direction, and the sensor <19+ is from (D) to point (A)
Move to a point.

Through the above operations, the copying fence returns to the state immediately before the copying operation start switch was activated, and preparation for the subsequent copying operation is completed. Regarding the movement of the sensor Q9), in addition to movement from point (C) to point (D) as in this embodiment, there are various other paths such as movement from point (C) to point (B). A similar effect can be obtained by using .

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, prior to the copying process, the reflection density of the background of the copy original is detected, and the optimum developing bias voltage is determined based on the inspection power, and the optimum developing bias voltage is determined during the copying process. Since this is carried out at a constant optimum developing bias bottom pressure, high-quality copies can be made without failure. Furthermore, since the one-time inspection of the background reflection of the copy document is performed while the copying machine is performing the pre-processing process, there is no reduction in the copying speed due to the automatic exposure function.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the main parts of the Kuzi photocopying machine, Fig. 2 is an explanatory diagram of the surface potential of the photoreceptor drum, Fig. 6 is a schematic diagram of the V6 arrangement of the conventional device, and Fig. 4 is a diagram of the present invention. FIG. 5 is a schematic bottom view of a copying machine according to an embodiment of the present invention, and is a three-line electrical diagram of the main parts of a copying machine according to an embodiment of the present invention. (8)...Magnetic roll, QCe...Development bias power supply, 111...Original stand force, α force...Copy original, Ua+...Exposure rung, 09)...Sensor, 2
G... Sensor support member % Shima... Sensor support member aS structure, M... Arithmetic processing circuit, 12! I... Control circuit owner Yoshihiro Kimoto Figure 1 Figure 2 Exposure, amount of light Figure 3 2 Figure 4 2θ

Claims (1)

[Scope of Claims] 1. A sensor that detects the density of light reflected from a copy document; and a sensor that detects the density of light reflected from a copy document; a sensor moving means for moving a predetermined distance; and a control means for determining a phenomenon bias pressure based on a detection output while the sensor is moving, and controlling the developing/earth printing pressure in accordance with the reflection density of the background of the copy document. Copy machine equipped with 2. The sensor moving means is comprised of a sensor holding member that holds the sensor at one end, and a sensor holding member driving mechanism that rotates the sensor holding member around the other end. Copying machine according to item 1.